A precise analysis of the capacity of a wireless downlink packet data system with a fair scheduler is presented. We assume the use of a transmit diversity scheme is operating at each link under the assumption of spatially correlated Rayleigh fading. Numerical results show that spatial fading correlation of the channel improves the capacity of multiuser diversity by reducing the space diversity gain of transmit diversity in each link.

We propose and describe a new configuration for splitting and combining operations of high-speed amplitude-modulated optical signals between the two interacting beams by using two-wave mixing in photorefractive Cu-doped (K0.5 Na0.5)0.2 (Sr0.61 Ba0.39)0.9 Nb2O6 (Cu-KNSBN) crystal. These operations are simultaneously achieved by changing the intensity ratio of the two incident beams. We also apply this scheme to a photorefractive pulse shaping in the time domain that consists of two amplitude-modulated beams that are coupled automatically through two-beam interactions in the crystal. Some preliminary experimental results are presented and discussed.

In this letter, base station placement is automatically determined from pre-defined candidate sites using a genetic approach, and the transmit power is obtained taking the interference situation into account in cases of interference-dominant systems. In order to apply a genetic algorithm to the base station placement problem, a real-valued representation scheme is proposed. Corresponding operators such as crossover and mutation are also introduced. The proposed algorithm is applied to an inhomogeneous traffic density environment, where a base station's coverage may be limited by offered traffic loads. An objective function is designed for performing the cell planning in a coverage- and cost-effective manner.

We propose a modified orthogonal transmit diversity (OTD) scheme, which can simultaneously achieve full path diversity and temporal diversity by using symbol splitting. Our proposed method is comparable to space-time spreading (STS) in performance and superior to STS in the cost and efficiency of base station RF devices.

A simple Minimum Rate Supporting Scheduler (MRSS) is proposed for HSDPA (High Speed Downlink Packet Access). MRSS guides the user selection in order to provide, if any, a prespecified minimum rate for each user. The simulation results show that MRSS successfully supports to keep the minimum rate up to fairly high traffic load, where existing methods fail, with tolerable degradation in throughput.

In this paper, we propose a resolution enhancement method for estimating direction-of-arrival (DOA) of narrowband incoherent signals incident on a general array. The resolution of DOA algorithm is dependent on the aperture size of antenna array. But it is very impractical to increase the physical size of antenna array in real environment. We propose the method that improves resolution performance by virtually expanding the sensor spacing of original antenna array and then averaging the spatial spectrum of each virtual array which has a different aperture size. Superior resolution capabilities achieved with this method are shown by simulation results in comparison with the standard MUSIC for incoherent signals incident on a uniform circular array.

In this paper, we propose a new algorithm of enhancing covariance matrix estimate to be used for estimating the directions-of-arrival (DOAs) of multiple incoherent signals incident on a uniform circular array. The underlying covariance matrix possesses a special theoretical property such as having spatial stationarity. The proposed enhancement approach based on the use of this property is found to provide improved DOA estimates in comparison to the unenhanced MUSIC for narrowband incoherent signals.

It is a critical design process to estimate the fractional errors of the Synthetic Aperture Radar (SAR) processor before implementation. The contribution of this paper is to identify the chief sources and types and to suggest an estimation technique for overall fractional errors of the space-based SAR processor using Range-Doppler Algorithm (RDA). Also, simulation is performed to the Experimental-SAR (E-SAR) processor to examine the practicability and efficiency of the technique, the results are discussed, and the solutions for problems are recommended. Therefore, this technique can be used to estimate the fractional errors of the space-based SAR processor using RDA.